Step ladder



FIG. 1 is a perspective view of a step ladder illustrating our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a right-side elevation view thereof;

FIG. 4 is a left-side elevation view thereof;

FIG. 5 is a rear elevation view thereof; and,

FIG. 6 is a top plan view thereof. 

The ornamental design for a step ladder, as shown and described. 